Unloader for compound fluid-compressors.



VV. PRELLWITZ.

UNLOADER FOR GOMPOND FLUID GOMPRESSORS APPLICATION FILED MAY 31` 1907.

1 ,O 1 9, 360. Patented Man'. 5, i912.

l W. PRELLWTZ. UNLOADER OR UDMPOUND FLUID GOMPRESSORS,

APPLICATION FILED MAY 31, 1907.

Patented Mar. 5, 1912.

' 5 SHEETS-SHEET 2.

` W. PRELLWITZ.

UNLOADER FOR GOMPGUND FLUID GOMPRESSORS.

APPLICATIGN FILED MAY 31, 1907.

Patentd Mar.5,1912.

SHETTS-SHEET 3.

' @66% @Ven/Z020 mwa' f W. PRELLWITZ.

UNLOADBR FOB. OMPOUND FLUID COMPRESSORS,

APPLICATION FILED MAY 31,1907.

1,019,360. Patented Mar.5,1912

5 SHEETS-SHEET 4 W. PRELLWITZ.

UNLODER 1FOR GOMPUND FLUID MPRESSORS.

APPLICATION HLED 14u31, 1907.

v i Patented Mar. 5, 1912.

' Y 5 SHEETS-SHEET 5.

unirsi) strarns Patriiivr orFicE.

WILLIAM PRELLWITZ, OF EASTON,"IIENIIT.SY-LVANIIA.,l ""ASSYIGNOR .TOINGERSOLL-RND COMPANY, 0F NEWTv YORK; Y., A CORPORATION OFNIE` JERSEY.

UNLOADEB FOB COMPOUND FLUID-COMPBESSORS. l

To all whom it may concern:

Be' it known'that I', WiLLiAM Pnnnmvrrz, a citizen of the United States,and resident ot" Easton, in'the county of Northampton and StateotiPennsylvania, have invented a new and useful Improvement in Unloadersfor Compound Fluid-Compressors, of which the following- -is aspecifica-Lion.

. My invention'relates to means` for unload-` ing compound iuidcompressors and 'consists broadly in novel niean's arranged toautomatically unload the compressor when the, pressure rises to apredetermined point and-load the coiiipi'essoi-ivlien the pressure fallsto a predetermined point, said means comprising an auxiliary receiver,the valve for opening and closing communication between the compressorand auxiliary receiver and a regulating device, such as a fluid pres--sure governed regulator. -connected to the -back ot the auxiliaryreceiver valve.

My invention further consists in means' for unloading and loading thecompound compressor step b v step as the pressure' rises r plane of andfalls to predetermined points, said means comprising` a plurality ofauxiliary receivers, valves arranged to open and close communicationbetween 'the compressor and the auxilia ry receivers and a pluralityr ofregulating devices, suchas fluid pressure governed regulators, connectedto the backs of the auxiliary receiver valves for unloading and loadingthe valves successively as the pressure -rises and falls.

This present-invention is also directed tol the novel means above setforth applied either- Sto both the-high and low pressure cvlinders'or tothe' lon'r pressure cylinder o a compound iiuid compressor.

Practical embodiments of .pressure cylinder, Fi 4 is a central verticalsection through tv e fluid pressure gov- .erned regulator which isshown' in comico-- Ation with my unloading meansfFig'. 5" represents acentral vertical section of the regulating valve, Fig.l 6 is a viewtaken in the the line A-A of Fig. 4, looking Specification olf LettersPatent.

.application sieri my 3i, 1907. serial N o. 376,703.

my inventionare represented -m the accompanying drawratented Mar. 5,1912.

Avin the direction of the arrows, Fig. 7 is a horizontal section takenin the plane of the line B-B'of Fig. 1i, looking in the direction of thearrows, Fig. .is a diagrammatic planview showing means for unloading andloading the low rassure cylinder only of the compoundrfluid compressor,and Fig. 9 is a diagrammatic planview showing a modified arrangement ofthe unloading means in which two iiuid pressure governed regulators aresliovvn for unloading and loading both the high and low pressurecylinders instead of form.

Proceeding-to describe the form shown in Figs. 1 tov 7 inclusive, thelowpressure 'cylinder-is denoted by 1, theA highpressure' four as shown inthe preferredcylinder by 2 and the intercooler by 3. The

pipe leadin from the low pressure cylintlie pipe leading from theintercooler 'to-the der to'the inter'cooleris denoted bye-and pipe whichleads from the high .pressure cylinder to thelfinal'reeeiver (notshown), is denoted by The main discharge valves of the low pressurecylinder' are denoted by 7 and the main discharge valves ofthe highpressure cylinder by 8. It is.to be understood that the compressor isdriven from any suitable source off-' power,V not shown herein.Auxiliaryrec'eivers 9 are provided for the low pressure cylinder andauxiliary receivers -10 are provided for the high presvsure cyl-inder.Valves 11 are providedl .for opening and -closing communication between'the low pressure cylinder and the apxiliary receivers 9',.andvalv'esidZareprovided for opening and closing communication between thehigh pressure vcylinder2 and the aux- -iliary receivers 10. Fouraiixiliary receiv-A ers 9 and their valves may lie-provided for at each.end thereof. Four- .au iliary receivers 1() and their valvcsmay bprovided for the highv pressure cylinder 2, communieatingl with .eachendthereof.- The hacks A the low pressure cylinder 1, communicating.

ico' I of theauxiliary receiver .'va'lvesare. brought into communicationvvith regulating devices,"

such" as `Huid pressure governed '.-regulators of the form-I disclosedin= Uniteldfstates Letters Patent No.' 514,839 .dated February 18,`1894, changed to suit a. cox'n'pound compressor'-, a.general-description o the construction, arrangement and operation ofwhich ton heads 15, 1'6 and bridge ports. 14", 14?.

"gbypi-essure upon onej or the other-of its 1F15 .to the valve -box '13fh fou receiver pressure." The main valve 14 ispro- 60 on the auxiliaryreceiver valves untilaf rei?y taining the main slide'valve 14e1 havingThis valveboxzis provided-with ports 17,

' 5 18, leading to atmosphere'l 'and ports 19, for 1,-.' theintercooler, 20 for the' auxiliary receiver .f 'valves of the loivpressure cylinder -and 21 -for the auxiliary valves ofthe hi h pressure'f cyliiider. lhe `main valve 11,1 1s operated piston' heads 15,116, VbyHujdaemiued. at

the rends ofy the -valve box through ports 22,

. .23, under the control ofen-auxiliary slide valve 2 4 in box25 whichis always open n gh'4 thefpassages 26,-27. A pipe 28leads fromthe-receivertothe space between the main'valve iston he'ads v15, 16 sothat-'this spaceand e in. terior of the. boliV 'arealways open to videdwith ports arrangedto open communication from. the backs of theauxiliary reeeivei1 ,valves on,V the. high and`low pressure cylinders toatmosphere or to the receiver 25 and intercooler respectively,'according to the position .of the valve.' lVhen-the main valve is inone position the auxiliary valves o' the high pressure cylinder-areloaded by having their backs open to receiver 'pressure 3othrough theport 21,' interior of ,boxrl and pipe 28, and the' auxiliary? 'receiverlvalves of the loiv pressure cylinder are loaded having their backs open.to intercooler'pressure, through the ports 20,142 and 19. W'hen the mainvalve is in its other osition, the .auxiliary receiver 'valves of t eVhigh ressur'e cylinder are unloaded by -having heir backs 4open toatmosphere through ports 2l, l-l ard 18, and the' auxiliary tje- 4oceiver valves of the' low pressure cylinder are unloaded by having theirbacks open toatmosphere through peras 20, 14 and 17.4 '.lbc top of theauxiliary valvebox'25 is provided with a cylinder 25) which iscpen etthe bottom to .the interior of theY said box: piston 30 is fitted toslide in the Under' 29, u/,hicii piston is arranged to move theauxiliary vulve 24 under the ini llvea'ce of: receiijfer pressure, Thisauxiliary 5f: vulve Qi iss-provided with upper, and lower bridge ports31, 32, and uppetand lovver through ports 33, 34.- The main valve box 13is pr'ovided with a port- 35- intermediate the ports '22, 23. Theseseveral'port-sarel.v so arranged that-tbe movement of the auxil- 'ligh bthe-.Huid within inatically reducing "pr'essor to a predetermined extentfixed by -therela'tive capacities 'of the compressor cylinderian'dauxiliary receiver. As the'fluid 125 pressure falls inthe receiver,

lary valve '.rill control the movement of the-y mamw'alve.: T he piston30 for-'o 'erating the auxiliary valve is weighted to iold theauxiliaryvalve in' position to leep the loa`d= determined high pressurehas been-rear:l ed; hv 'means of a Weighted arm 36, the Weights 257 on-whielrnnay-be so re lated that' theI hack o'thb 'auxiliary receivervalves will 'oe-unloaded by the movement of the mainl inder and thevalve of an auxill y 10 atv the other end of. the hi iliary receiversVat theA op 'high pressure cylinder.'

-ceiver valve 'by-opening the valve ,under the'control 'of the movementof the auxili'aryvalve when said predetermined high'pressure' has beenreached., In `the form being described, four of these fluid pressuregoverned regulators are shown, each-regulator bein arranged'to controlthe unloadingof a 'v a ve of an auxiliary, receiver 9 at one end of thelow pressure cylary receiver gh pressure 75. cylinder. In the fornishownin Fig. 9, two fluid pressure overnd regulators only are shown, eacregulator communicating[with the backs ofthe valves of two auxiliaryreceivers at the opposite ends of the low pressure cylinder' and theVvalves of two .aux-l psite ends of the Fig. 8,' a form is shown in'which the low' p only is provided with auxiliary' receivers and r'eguators for their valves. The several forms shown therein are.illustrating the point'that any number of auxiliary -receivers may be"employed andv any number of regulators to suit different requirements. yThe operation of the simplest forni of n'f' invention Wouldbe as.follows.l Anauxil- 5 lary receiver cfu predetermined size is con--nected to 'the lowjpressurecylinder and'a regulating device, such 'as -afluid pressure governed regulator, islprovided for the aux-V iliaryreceiver valve. When `the compre. r starts, the pressure is raised in.the auxiliary receivercorrespondin tothe rise' of p'ressure inthesys'ten. ter the' pressure has been. raised .to its regular Workingcondir tion, -the'auxiliary receiver valve tends to remain closedbecause of the ,receiver on the back oft-he valve. When the pressure hasbeen raised to a predetermined 'high point, thel .regulator beingcontrolled by receiver pressure Willautomat-L cally unload .the 'back ofthe auxiliary re- 110 eeiver valve by opening the snm'e to atmos phere,Ythus allowing the fluid under prssure to be forced from thecylinderinto the auxiliary receiver on the forward stroke of the piston and topass back frein the N auxiliary receiver into lfor the purpose of ofthe; valve spring, which 4is .made veryv t, is less than the pressure-onthe valve .120

the. cylinder; thus auto!1 the power of the com# the regulator auxiliaryre- -back ofqthe. same to receiverepressure, thus closing the ,Will`automatic'xallyload"l the 'valve and 'perniilttliiigythe compressor to13e ressure cylinder 85 the pressure from 1'05 the cylinder on theft-Aretu'rn stroke of the piston, the unloaded valve remaining open so long,as -the power,

I lloaded,-A 'the interc'ooler pressure. will fall. in= proportiont thecapacity of the aux` rota-,seo Y again' pe'ratev-ndec power. 'In this;

form, ,astlie"low pressurecylinder is un iliary Itccfeivfei- L to reducethe vload on the low ressiiref-cylinder,4 the high. pressure cylin cs.takingftheliuid from the intercooler and'con1pressing it to the finalreceiver. While thiswould be satisfactory in scmein'st-ances, it wouldnotbe so economical. It' would red'uoethe capacity of the machine andreduce the amount of power reuired' to drive iti the low pressure cyl-1n er would not do 'its proportionate amount of work and there would notbe as much heat abstracted. byvv the intercooler. 1t`is obvious that byvarying the size of the auxiliary receiver,'t lie compressor cylindercanbe entirely unloadedY or only partially u-nloaded, dependingupon thesize of the aux-.f 'iliary receiver:

o; obtain the ful-l benefit of' extracting as much. heat as possiblefrom the fluid, it.- is preferableto use these unloading devices 1nconnection withboth the h igliand lowpressure cylinders, the relativecapacities ofthe auxiliary receivers for the high and low pressurecylinders being'such that with -normal pressures, each c 'linder will"have aproportionate amount o clearance, as for instance, ii' theauxiliary' re ceivers for the low pressure cylinder reduce its capacityone-third the auxiliay receivers for the high pressure cylinder willreduce its capacity 'one-third. With this arrangement the intercoolerpressure wouid remain-'substantial'ly constant and each cylinder wouldbe compressing the same number of compressions, t-hus producing the mosteconomical results'. If it is desired to unload' the compressor step bystep, a plurality of sets of' auxiliar .receivers areprovided for thehigh and ow pressure cylinders and the regulators for the differentauxiliary receiver valves are set by means of varying their weights 37to successively unload the auxiliary receiver val-ves as the fluidpressure rises-to :predetermined points and load vsure falls and this isa valuablefeature ofmy inventiornas .it eliminates' all shocks' to themachine .asthe load is thrownV on and backward loadsA onv the machine' 4nearly uniform wouldbe to first ,simultaneously un- -load one auxiliaryreceiver valve at the of the high pressure cylinder and then silmultaneously unload the auxiliary -receiver compressor, o auxiliaryreceiverstherefor,

` valves for opening or closing communication valve at the back end ofthe low pressure cylinder and the auxiliary receiver valveexpanded.lftheunloaded valves' regulating device I wish to include 'an .sivelyattained' pressures. oi. One way of. accomplishing this result Y 3. Thecomb'n'ation-vviththe highandflow and at the same time keep the-forwardand -or closing. communication between the cylwill beagain givenbackto1the-machineolii" the return stroke as the volume of fiuidjs closeat'the end of the piston strokefaiyay from said valves, due to thereduction-f ff 'im pressure below the power of their sp'ril i'fzjsgf'"f1they will be opened again assoon as thepisr ton starts toward saidvalvesand'will' 'r` ""`8f0 main open until the/pressure in the'auxliai'yworking with; the- 'auxiliar-y receiver valves closed,- it will "be seenthat-the auxiliary. receivers remain full of fluid atmaximum pressure asthe valves l prevent-the iuid from passing back into the,` cylinder. AAttcntionis called tomy co-pending ap'' plication'led of even dateherewith, Serial No. 376,702, in .which nnuaire. pendinggf* "ifdirected-to 'the loading and unloading` flu-id compressors of any typebya ntnie'l".`-

means while this present application isidi- 95 rected toA the loadingand-unloading ofa L compound fluid -compressor of any type'similarfmeans.

It is to be understood that by the term 'T100 mechanical, electrical or'fluid means'whic can be employed for carrying out the ob-' jects of myinvention; hen-ce I do not wish1 to limit myself tothe particularregulating del vice hcreinshown and described, but )05 What I claim is:j 1. The combination. with the high and low. pressure cylinders of acompound iiuidcompresser, of auxiliary receivers therefor, and means foropening or closingcoinrrmnication between the cylindersand theirauxiliary -receivers at successively-attained ressure's.

. 2. The combination with the igh-.and-lowpressure cylinders off a;ccmpoundiluid'comfpressor,' o auxili ary receivers4 tlu'arefor, and 1.i6fluid pressure controlled;means:foropening` or closing communicationbetween the cylin-` ders and'theii'. auxiliary receivers atv succes-j12e pressure cylindersof-za'compoundlluidzcom-- 'I pressor, of auxiliaryreceivers therefor, a nd, fluid pressure controlled valves for openlnginders and. their auxiliary receivers at suc-v cessively attainedpressures.

receivers. is. reduced to a -pointbelow the@` e betiveen thecylindeisand their tained pressures dd 0 :fofthe-valves forl successvel'means u 'ndependentof' the p uirrping mechanism'for unloading it insucingit in successive well 9- Illacompound-llmd comprcssonthe,

compressor, o

auxiliary receivers at successivelya unloading devices for thesaid-valves.

5. The combination' -with' the' highand low pressure 'ylinders of 'acompound {luidceivers at successively attained pressures and.

#fluid pressure controlled unloading devices 'forftlie-said valvesfJoundfiiuid compressor, the.

6 In`a com; combination with I pumping mechanism, fval'ves of the 'L In'a compound fluid compressor', the

.combination -ivith' 4.pumping mechanism, of fluid .pressure controlledmeans independent` ofthe valves of the pumping mechanism for unloadingit in Asuccessive well defined steps.

8. In a compound fluid compressor, the combination .with pumpingmechanism, of

i means, independent of the valves. of the pumping meelxanisniforloading or unload' defined steps.

combination with4 pumping mechanism-,Tof fluid pressure controlled meansindependent of the valvesof. .the pumping mechanism for loading en-unloading' 4it iii-successiveiivell defined steps.

10. The combination with the cylinders of a compound iiuid compressor,of unloading devices` indepe ndent of the compressor valves, fitted tooperate at different succes'- .,1I, .L. Th e combi ationwitlithevcylindcrs of a compoundiiuid compressor, of fluid pressure,controlled unloading devices .independent of the compressor valve's,fitted to operat at different successively 12.-l.'l`he combination-withthe .low pressure cylinder of a compound fluid compressor, of auxiliaryreceivers .iherefor, valves for openingnml closing coinii'ninication beltween the low pressurel cylindcuand the auxiliary receivers and meansconnected to thc backs ofthe valves for successively unloading t li emas different predetermined high pressures are reached. i r13,;Thejconibination with siirecy-lindei of a compound fluid compres sor, ofauxiliary receivers, therefor` .valves for opening andelosingcommunication between, the lowprcssure cylinder and the auxiliaryreceivers `and fluid pressure controlled' means connected to vt-liebacks of the valves unloading'them as different predeteriiiiii'cd highpressures are reached.

cylinder of a compound Lfii'ild compres.-

auxiliary receivers therefor,f valves for opening or closingcommunication between the cylinders and their auxiliary relowpressure'cylinder and the'auiluir 'receivers, andregulators connected ttiling ack werden asdilierentfpredeterinine 'j' high are reachcdxf n 15.The combination .with the low pres-- sure 4'cylinder o a' compound Huidcompress'onimof auxiliary receivers,l valves .for :opening and closingcommunication befw f, .the loiv pressure cylinder and' the aux'ili i;receivers, and Huid pressure goverxiwu latorsconnected to the backs ofthe -va ves for successivelyunloading them as differentpredeterminedhigli pressures are reached 16.' .The'combinationwith thelopr pressure; '-80 :cylinder of a compound fluid compissqryoffdetermined ,ingtlie ,valves as the' pressure falls to prds i .ccivers,and'iuid pressure controlled means fpressure rises to for successivelyloadingthe valves as `t`lie-.;' Epressure falls to -automatically uncompressor step by'step.

'sure .cylinder 4and the auiiilia 'and regulators for. successivelyunloading 'the valves as ihe'pressure rises to predeter' )attainedpresmined points',

the -loiv pres;

. auxiliary receivers tlierefor,'valves for`o1ii i`\j ing and closingcommunication lietweentlie? glow pressure -cylin'derand the auxiliaryre-' '.ceivers," and means for A-sujiqzessivcly un cada' g5 ing thevalves as the pressurerises to pre` points and for successively load-=tei-mined points, for automatically unload-.

17. The combination 'ivitlitlie low pressure auxiliary receiverstherefor, valves for opening and closing communication between the lowpressure cylinder and the auxiliary refor successively unloading thevalves as'the i predetermined 'points and predetermined points; for lngoading and yloading thes'f- 18; The combinationwith loiv pl-feiirecylinder of a compound fluid.compresso`r, of auxiliary receivers, valvesfor ohpening and Iclosmg communication between t mined-points and forsuccessively loading 11o the valves as the pressure -falls topredeterfor automatically unloading. and loading the compressor step bystep.

19L The combination with the low pressure cylinder of a-eoinpound fluidcompressor, of auxiliary receivers, valves. for opening andclosinglrcommunication between the low pressure cylinder and the' auxiliaryreceivers, and fluid pressure governed regulators for successivelyunloading thevalves Ias the res- "sure rises to predetermined' pointsfori'.

` successively loading the valves as the ,pressure falls torcdeterminedfpointsrfor auto` 4 pressor step by step. 20. Thecombination witli tli'e"higli and low pressurecylinders eta. compoundfluidi.

compressor,of .auxiliary receivers therefor? valves'for openin tandclosinglcommnca-r :ing and loading the compressorstep by step,

'matically un oading"' and loadi'iiggtli'e contr;

Afor unload ilng the compressor step. by step.

21. The combination with-the` high and low pressure .cylinders of acompound fluid 'compressor, oiauxiliary receivers therefor,

valvesfor opening and closing c o'nnnunieation between the high and lowpressure cylinders and their auxiliary receivers and fluid pressurecontrolled means connected .to the backs of theV valves for successivelyunload-y ing them as dillferent predetermined *high pressures arereached, for unloading the con'xpressor step by step. A

22. The combination with the high andlor pressure.cylinders of acompound fluid compressor, of auxiliary receivers, valves for openingand closing.communication between the cylinders and their auxiliaryreceivers and regulators connected .to th'ebacksof the valves forlsuccessively unloading theml as different )rcdetermined high pressuresarereached, or unloading the compressor step bystep.

23. The combinationwith the'high and low pressure cylinders ofacom'poundiluid compressor, of auxiliary receivers, valves' for openingand closing communication between the cylinders and their. auxiliaryreceivers,- and fluid pressure governed regulatorsfcon-l nected to thebacks of the vvalves or'succesv' sively unloading them asdifierentprede' termined high pressurcs'are reached, fofr pnloading thecompressor stepby step.-

24. The combination with 'the high and lour pressurecylinders of acompound-fluid compressor, of auxiliary'receivers therefor, valves foropening and. closing communication between the hlgh and loirA pressurecyl-I inders and their auxiliaryrecelversl and means for' `successivelyunloading-the valves as the pressure rises to predeterminedfpoints- Aandfor successively ,loading the'gyalfves as the pressure talls topredetermlned.;points, the

The combination with the high and low pressure cylinders of a. compoundfluid compressor, of auxiliary receivers therefor,1 .valves -for openingand closing communica- A tion between the high -and low Hpressurecyl? Iinders and their receivers and.

uid pressureA controlled means' ffor' successively unloading the. valvesas-tl'ie-'pressure rises to predeter# mined points and for successivelyloading' the valves the pressure fallstm-predeterf lmined points, -iorautomatically unloading' andloading the compressor step by step.

26. The combination with the high and loir pressure cylinders of acompound fluid compr ssor, oit auxiliary receivers, valves for upenn ,fund closing communication' between and 4regulators for successively'unloading the valves as. the pressure rises' to predetermined poin'tsandfor successively loading the valves as the pressure falls topredetermined points,y for autr'miatically unloading and loading thecompressor step yby step.

27. The combination' with the high and low pressurevcylinders 'ofcoin-pound zfluid compressor, ofauxiliaryreceivers, valves for cpenin rand-closing communication between t-he cy i.ndcrs.- and' theirauxilia'ry-receivers and fluid, pressure governed' regulators for successivelyunloading the valves as thepres- .su're'rises 'to predetermined pointsand for successively loading'the valves as the pres` sure 'fallslo'predeterinined points, for automatically unloading and loading the"com- `pressorstep by step.

28. The'combination with the high and low pressure cylinders of acompound fluid compressor, Qf-a" plurality 'of auxiliary reoeiversforea'clr cylinder,y valves for opening and closing communication betweenthe high andV low pressure cylinders-and their auxiliary-receivers' andmeans connected to the backs of. the valves for successively unloadingthem-as' diierentv predetermined high pressures'a-e reached, rerunloading the compressor step byste'p, r

' 29."'l`h e combination'\vitl1"tl1e"l1igii and glow; pressure.cylindersof a :com pound ll uid compressor', `olf-a"ilurality of auxiliaryreceivers for each cy inder, valves fr opening .and closingrcommunication between the high 'and .-loiv ,pressure cylinders andftheir auxiliary receivers and fluidr pressure controlled means connectedY totlie backs. of the valves .for successively unloading them as'diil'erent predetermined high y pressures are.v reached, Afor unloadingthe compressor step by step,

. 30.*The. combinationff with vthe high and low pressure cylinders-oi?4a compound -fluid compressor, of a plurality of :auxiliary rcceivers foreach cy inder, val ves Torf'opening and closing communication -betwccn'the cyl'- inders and theirl auxiliary receivers, and regulatorsconnected -to the backsiof "the valves for successivelyunloadingthem asvdilferentpredetermined high pressures. 'are reached, for unloading thecompressor step by step.

low pressure cylinders of 'a compound fluid compressor, olf-a -pluralityoauxiliaryipcthe cylindersand their auxiliary receivers compressor, ofa, plurality4 of auxiliary re- '3.1.' The combination with the high and,

ceivers foreach cylinder, valves for opening i and closing communicationbetween the high and low pressure cylinders and their auxiliaryreceivers and means for successively unloading the valves as thepressure rises to predetermined points and for successively loading thevalves as the pressure falls to redetermined points, for automaticallyunoading and loading the compressor step by ste 3. The combination withthe high and `lovv, pressure cylinders of a compound fluid compressor,of a lurality of auxiliary reoeivers for each cy inder, valves foropening and closing communication bet-Ween the high and low pressurecylinders and their auxiliary receivers and Huid pressure controlledmeans for successively Vunloading the. valves 'asthe pressure rises toredeterinined points and for successively loa ing the valves as thepressure falls to predetermined points, for automatically unloading andloading the compressor step by step.

B4, The 'combination -With the high and low pressure cylinders of a.compound i'iuid compressor, of a plurality of auxiliary receivers for.each cylinder, valves for .Opening and closiiil communication betweenthe cylinders an their auxiliary receivers, and

-.regulators for successively unloading the valves as the pressure risesto predetermined points and for successively loading the valves as thepressure falls to predetermined points, for automatically unloading andloading the compressor step by step.

35.The combination with the high and low pressure cylin ers of acompound iiuid compressor, of a lurality of auxiliary receivers for eachcy inder, valves for o ningv and` closin conimuni'cation'between t ecylinders yan their auxiliary receivers and Huid pressure overned reilators for suc! cessively unloa ing the va .ves asthe pres- Q' surerises to predetermined points and for successively loading tlie valvesas the presfsure falls to redetermined points,l for-auto'- Amatically uoading and loading the com- .presser s tep by step.

`,'36.'The combination with v lowpressure cylinders of a compound fluidthe high ana-- Y `pressure controlled means for openingandclosingcommunication between the cylinders' and their auxiliaryreceivers, the` relative capacities of the auxiliary receivers of thehigh and, low pressure cylinders being so proportioned that theintercooler, pressure will remain substantially constant.

38. The combination With-the high andlow pressure cylinders o'f acompound fluid compressor, of a plurality of auxiliary receivers foreach cylinder the relative capacities of the auxiliary receivers of thehigh.

and low pressure cylinders-being so proportioned that the intercoolerpressure Will .res-v main substantially const-ant and means forsimultaneously opening and closing -communication between each'oftheeorresponding auxiliary receivers and its cylinder.

.39. The combinationwitli the higi'iand low pressure cylinders of acompound fluid compressor, of a plurality of auxiliary receivers foreach cylinder the relative ca acit-ies of the auxiliary receivers of theiigh and low pressure cylinders being so proportioned that theintercooler pressure will remain substantially consta-nt and iuidpressure controlled means for simultaneously opening and closingAcomii'iunication between each-of the corresponding auxiliary-receiversand its cylinder i `fI'n'testimony, that l claim. the foregoing.

as my invention, I 'liave signed my naine in resencelof two witnesses,this 25tlr day ofj Wnliimn: PRELLWITZ.

F. GEORGE BARRY,

HNBY THIEME.

